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Title: LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).

Abstract

This report summarizes our findings during the study of a novel homogeneous epoxidation catalyst system that uses molecular oxygen as the oxidant, a ''Holy Grail'' in catalysis. While olefins (alkenes) that do not contain allylic hydrogens can be epoxidized directly using heterogeneous catalysts, most olefins cannot, and so a general, atom-efficient route is desired. While most of the work performed on this LDRD has been on pincer complexes of late transition metals, we also scouted out metal/ligand combinations that were significantly different, and unfortunately, less successful. Most of the work reported here deals with phosphorus-ligated Pd hydrides [(PCP)Pd-H]. We have demonstrated that molecular oxygen gas can insert into the Pd-H bond, giving a structurally characterized Pd-OOH species. This species reacts with oxygen acceptors such as olefins to donate an oxygen atom, although in various levels of selectivity, and to generate a [(PCP)Pd-OH] molecule. We discovered that the active [(PCP)Pd-H] active catalyst can be regenerated by addition of either CO or hydrogen. The demonstration of each step of the catalytic cycle is quite significant. Extensions to the pincer-Pd chemistry by attaching a fluorinated tail to the pincer designed to be used in solvents with higher oxygen solubilities are also presented.

Authors:
 [1];  [1]; ; ; ; ;  [2];  [3];  [1]
  1. (University of Washington)
  2. (New Mexico Institute of Mining and Technology)
  3. (University of Washington)
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
878587
Report Number(s):
SAND2005-6754
TRN: US200611%%342
DOE Contract Number:
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; ALKENES; CATALYSIS; CATALYSTS; CHEMISTRY; HYDRIDES; HYDROGEN; OXYGEN; SOLVENTS; TRANSITION ELEMENTS; Alkenes.; Catalysts.; Oxygen-Analysis.

Citation Formats

Goldberg, Karen, Smythe, Nicole A., Moore, Joshua T., Stewart, Constantine A., Kemp, Richard Alan, Miller, James Edward, Kornienko, Alexander, Denney, Melanie C., and Cetto, Kara L. LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).. United States: N. p., 2006. Web. doi:10.2172/878587.
Goldberg, Karen, Smythe, Nicole A., Moore, Joshua T., Stewart, Constantine A., Kemp, Richard Alan, Miller, James Edward, Kornienko, Alexander, Denney, Melanie C., & Cetto, Kara L. LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).. United States. doi:10.2172/878587.
Goldberg, Karen, Smythe, Nicole A., Moore, Joshua T., Stewart, Constantine A., Kemp, Richard Alan, Miller, James Edward, Kornienko, Alexander, Denney, Melanie C., and Cetto, Kara L. 2006. "LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).". United States. doi:10.2172/878587. https://www.osti.gov/servlets/purl/878587.
@article{osti_878587,
title = {LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).},
author = {Goldberg, Karen and Smythe, Nicole A. and Moore, Joshua T. and Stewart, Constantine A. and Kemp, Richard Alan and Miller, James Edward and Kornienko, Alexander and Denney, Melanie C. and Cetto, Kara L.},
abstractNote = {This report summarizes our findings during the study of a novel homogeneous epoxidation catalyst system that uses molecular oxygen as the oxidant, a ''Holy Grail'' in catalysis. While olefins (alkenes) that do not contain allylic hydrogens can be epoxidized directly using heterogeneous catalysts, most olefins cannot, and so a general, atom-efficient route is desired. While most of the work performed on this LDRD has been on pincer complexes of late transition metals, we also scouted out metal/ligand combinations that were significantly different, and unfortunately, less successful. Most of the work reported here deals with phosphorus-ligated Pd hydrides [(PCP)Pd-H]. We have demonstrated that molecular oxygen gas can insert into the Pd-H bond, giving a structurally characterized Pd-OOH species. This species reacts with oxygen acceptors such as olefins to donate an oxygen atom, although in various levels of selectivity, and to generate a [(PCP)Pd-OH] molecule. We discovered that the active [(PCP)Pd-H] active catalyst can be regenerated by addition of either CO or hydrogen. The demonstration of each step of the catalytic cycle is quite significant. Extensions to the pincer-Pd chemistry by attaching a fluorinated tail to the pincer designed to be used in solvents with higher oxygen solubilities are also presented.},
doi = {10.2172/878587},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2006,
month = 2
}

Technical Report:

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  • The overall purpose of this LDRD is multifold. First, we are interested in preparing new homogeneous catalysts that can be used in the oligomerization of ethylene and in understanding commercially important systems better. Second, we are interested in attempting to support these new homogeneous catalysts in the pores of nano- or mesoporous materials in order to force new and unusual distributions of a-olefins to be formed during the oligomerization. Thus the overall purpose is to try to prepare new catalytic species and to possibly control the active site architecture in order to yield certain desired products during a catalytic reaction,more » much like nature does with enzymes. In order to rationally synthesize catalysts it is imperative to comprehend the function of the various components of the catalyst. In heterogeneous systems, it is of utmost importance to know how a support interacts with the active site of the catalyst. In fact, in the catalysis world this lack of fundamental understanding of the relationship between active site and support is the single largest reason catalysis is considered an 'empirical' or 'black box' science rather than a well-understood one. In this work we will be preparing novel ethylene oligomerization catalysts, which are normally P-O chelated homogeneous complexes, with new ligands that replace P with a stable carbene. We will also examine a commercially catalyst system and investigate the active site in it via X-ray crystallography. We will also attempt to support these materials inside the pores of nano- and mesoporous materials. Essentially, we will be tailoring the size and scale of the catalyst active site and its surrounding environment to match the size of the molecular product(s) we wish to make. The overall purpose of the study will be to prepare new homogeneous catalysts, and if successful in supporting them to examine the effects that steric constraints and pore structures can have on growing oligomer chains.« less
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